Refrigeration system servicing unit with dispensing pump and connector



United States Patent Ralph E. Bruce 6342 Seton Hill, Dayton, Ohio 45459[21 Appl. No. 754,917

[22 Filed Aug. 23, 1968 [45 Patented Nov. 10, 1970 [72] Inventor [54]REFRIGERATION SYSTEM SERVICING UNIT WITII DISPENSING PUMP AND CONNECTOR11 Claims, 5 Drawing Figs.

Primary Examiner-Laverne D. Geiger Assistant Examiner-R. J. SherAttorney-Norman R. Wissinger ABSTRACT: A servicing apparatus forrefrigeration systems air-conditioners,

particularly automotive comprising a refrigerant supply reservoir, anovel metering liquid refrigerant dispensing pump characterized by acircumferentially split cylinder surrounded by a fluid chamber havingtwo ports connected by conduits to said supply reservoir. a vacuum pump,and a connector yoke assembly The connector assembly comprises ahigh-pressure chamber and a lowpressure chamber, each of which isassociated with a pressure gauge and with a fitting for connectionrespectively with the high-pressure and low-pressure sides of therefrigeration system, a connector fitting and passage in communicationwith both of said chambers and adapted for selective association withthe said liquid dispensing pump and said vacuum pump, and a valvedpassage allowing communication between said chambers when there is nopressure in either of them and for isolating the two chambers when arelatively higher; pressure exists in the high-pressure chamber. Theregrigerant 1 dispensing pump is of the positive displacement volumetricvariety wherein the total volume of refrigerant dispensed is dependentupon the number of cycles of pump operation, and automatic means areemployed for counting such cycles and automatically stopping the pumpwhen the propernumber hasbeen reached. The refrigerant dispensing pumpmay be provided with temperature responsive means for changing theeffective volume of the cylinder within which the pump piston operates.whereby a constant weight of refrigerant may be dispensed for a givennumber of cycles, regardless of thermally induced changes in the densityof the refngerant.

,5 24-15 ll ll Patented Nov. 10, 1970 Sheet INVENTOR I RALPH E. BRUCEATTORNEY Patented Nbv.10,1970 3,538,961

Sheet or 3 v 1 FIG-3 nvvewron RALPH E. BRUCE ATTORNEY FIG-4 I PatentedNov.10,1970 I 3,538,961

Sheet 01' 3 I IN VE TOR v RALPH E. BRUCE A TTOR/VEY REFRIGERATIONSYSTEMSERVICING UNIT WITI-l DISPENSING PUMP AND CONNECTOR BACKGROUND OF THEINVENTION 1. Field of the Invention The present invention is in the formof a servicing unit for refrigeration systems, especiallyair-conditioning systems such as those in automotive use, and isprincipally composed of a refrigerant supply reservoir, a metering anddispensing pump and a connector uimembly to facilitate the operativeassociation ofthe unit with the system to be serviced.

2. Description ofthe Prior Art A common failing of closed refrigerationsystems, particularly recurrent in automotive air-conditioners, is lossof the refrigerant fluid; and the repair and maintenance of such systemstherefore regularly requires the replacement of such fluid. Because therefrigerant is necessarily characterized by low boiling point, highvolatility, and high vapor pressure, the procedures and devices involvedin such servicing have been complicated and have had to be carefullysupervised and controlled. A particularly troublesome complication hasresulted from the refrigerants response to temperature changes, eitheras a matter of changes or differences in the ambient conditions underwhich the refrigerant is stored or supplied, or as a matter of heatdeveloped by the operation of the mechanism to handle it. By way ofexample, the metering and/or dispensing pump which has been employed forsuch purposes in the past generates sufficient heat during operationthat the refrigerant in the pump or in the immediate area of the pumphas exerted a vapor pressure which is greater than that of therefrigerant in the supply vessel, as a result of which the desiredmovement of the fluid has been prevented, or at the very least has beendifficult to maintain or to control with the degree of accuracyrequired.

Because the volatile refrigerant in any closed system, whether it be inthe supply tank or in the refrigeration system being serviced, willexist partly as a liquid and partly in a gaseous state, it is the weightof the refrigerant introduced into the system which is the onlyprecisely controllable factor. ln response to this, the prior art hasresorted to the two-step process of first isolating the desired weightof the refrigerant, and of then introducing the isolated faction intothe system, Weighing techniques and devices being what they are however,purely gravimetric treatment of the refrigerant has not lent itself toautomation and has required time-consuming interruptions in theservicing of a unit and in the manual performance of the weighing andisolating steps. At the same time, the apparatus has been expensive andcumbersome.

In what is perhaps the most popular variant of this prior art technique,for example, the desired weight of the refrigerant has been isolatedvolumetrically by the use of a volume measuring device with manualadjustment means for adjusting the volume for different temperatures tocompensate for the different fluid densities at such temperatures. Theuse of this device has of course required a time-consuming interruptionwhile the volume is being thus adjusted; and experience has shown thatmany servicemen will not take the time to make the adjustment, as aresult of which a highly inaccurate charge may be used.

Perhaps a greater disadvantage of any of the prior art devices involvingthe pre-isolation of the desired amount of refrigerant, whether it isdetermined gravimetrically, volumetrically, or by a combination of both,is that the refrigerant thus isolated again exists as both a liquid anda gas within the isolation chamber, with the result that the removal ofall of the isolated faction from the chamber and its insertion to thesystem is impossible, primarily because as refrigerant is withdrawn, thepressure within the chamber is steadily reduced. On a hot day forexample, the removal of part of the refrigerant from the isolationchamber will cause the balance of the liquid remaining therein to boiloff and the reduction in temperature attending the rapid evaporationlowers the pressure in the isolation chamber to the point that no flowcan take place therefrom, even in response to pumping action. When thisoccurs, it has not been uncommon for the operator to invert theisolation chamber in an attempt to evacuate it by pouring the liquiddirectly into the system. When this is done, the liquid damages thevalves in the system and washes away the lubricant on the parts thereofto the extent that in most cases th system is thereby renderedunworkable.

ln other cases, the prior art has attempted to charge refrigerationsystems by volumetric control of the refrigerant through the use ofconventional positive-displacement metering and dispensing devices whichhave either been totally inadequate in reasonably controlling the amountof fluid supplied to the system or have required a variety of variousauxiliary controls which have further complicated both the apparatus andthe operating procedures. Particularly have the control problems beencritical in the servicing of small refrigeration systems such asautomotive air-conditioners in that they are generally operated bypersonnel who are not accustomed to precise manipulation and who, inmost'cases, do not have the time or the temperament to give theoperation the constant attention it requires. For example, many of theprior art servicing units involve an auxiliary heating unit to bring therefrigerant in the supply reservoir to a known tem perature sufficientlyabove ambient temperature that a pres sure differential between thesupply tank and the pump will be constantly maintained. This expedientis of course subject to the obvious objection that it artificiallyincreases the pressure of the fluid being handled and, therefore, theproblems of sealing the apparatus and preventing its explosion.Moreover, the heating unit itself requires sophisticated controls toinsure proper temperature of the refrigerant supply over the broad rangeof ambient temperatures that are likely to be encountered. Theparticular severity ofsuch problems in servicing automotive units, forexample, is apparent when it is considered that much servicing will bedone out-of-doors where the supply tank may normally be relatively coldand considerable time will be required to bring it to the temperature atwhich satisfactory operation can be expected.

ln addition to all of the foregoing, when it is considered that therefrigeration systems to be serviced by the device of this invention arethemselves designed to handle the refrigerant under both the highpressures of compression and the low pressures of evaporation and heatremoval and must therefore be carefully manipulated while refrigerant isbeing evacuated or introduced, it can be seen that the mere associationof any servicing unit with such a system can require detailed skills notnormally possessed by automotive-service personnel. The effect of suchcomplications, added to those derived from the nature of the refrigerantabove outlined, has been that effective repair of automotiveair-conditioners has heretofore been achievable only in manufacturingplants or in carefully supervised servicing stations wherein constantattention is given to the training of servicing personnel.

SUMMARY OF THE lNVENTlON it is accordingly an object of the presentinvention to provide an improved, simplified apparatus for the servicingof refrigeration systems, particularly air-conditioners of the typeemployed in motor vehicles.

Yet another object of the invention is to provide a novel metering anddispensing pump for refrigerants and other fluids characterized by lowboiling point and high volatility, which is capable of metering anddispensing a controlled volume of such fluid while maintaining the samein a liquid state without the necessity for auxiliary temperature andpressure control devices.

Still another object of the invention is the provision of a refrigerantmetering and dispensing refrigerant pump capable of supplying acarefully controlled weight of refrigerant material, which, thoughmeasured volumetrically, will remain constant in spite of thermallyinduced density changes thereof.

Still another object of the invention is the provision of a servicingapparatus for selectively evacuating and charging a refrigeration systemsuch as an automotive air-conditioner which may be simply andconveniently associated with the system to be serviced and will requirea minimum of attention and skill on the part of the user.

To achieve these and other objects which will appear from the followingdisclosure, the invention embodies first a novel refrigerant storage,supply, metering and dispensing assembly comprising a novel metering anddispensing pump characterized by a filling or input passage and avapor-releasing, bubble-return outlet or passage, both in associationwith a relatively elevated supply tank or reservoir from the bottom ofwhich the refrigerant liquid will flow gravimetrically through the inputpassage into the pump and the released vapor will rise to emerge withinthe reservoir at a point above the level of the liquid refrigeranttherein, The pump itself is of the positive displacement, reciprocatingpiston variety which departs however from the prior art in that thecylinder in which the piston moves comprises two separate sections whichare axially spaced within a jacket which defines a liquid-filled chamberaround at least that portion of the cylinder to be filled with fluidunder the influence of the piston and the circumferential opening intothe cylinder defined by the axially spaced sections thereof. Theliquid-filled chamber thus defined has two ports; viz., an inlet portwhich is connected by a suitable conduit to the lower portion of anelevated refrigerant supply tank or reservoir at a point below theliquid level normally maintained therein, and a vapor-release orbubble-return port, which is connected by a suitable conduit to theelevated supply tank at a point thereon above the level of liquidnormally maintained therein. ln lieu of connecting the vaporrclcasingbubble-return conduit directly to the upper portion of the supply tank,the conduit may be associated with an opening in the supply tank at ornear the bottom thereof, which, however, is supplied with a stack orconduit extension which rises through the liquid maintained therein andis vented to the gaseous atmosphere within the tank but above theliquid. At all times during its operation, the pump is so mounted thatthe vapor releasing port of the chamber is elevated relative to theinlet port.

The two segments of the cylinder of the pump as above described areaxially aligned and may be characterized as a first piston orplunger-housing segment and a second metering and dispensing segment.While the first of these corresponds somewhat to conventional pistonpumps wherein packing and sealing means are contained for isolating thepiston during its reciprocating movement therein, the second or meteringand dispensing cylinder is provided with a novel concentric cylindricalextension sleeve slidable therein, in response to the movement of thepiston. This arrangement of components is such that as the piston movesforward the periphery of its face or head engages or seats against theopposed edge or face of the slidable cylindrical extension sleeve,thereby to close the metering forward chamber in which the extensionslides, As the piston then moves forward, it pushes the slidableextension ahead of it for the balance of its stroke, thereby to displacethe fluid from the chamber in which it has been previously measured.Upon the completion of the displacement cycle, the piston returns to itsoriginal position and means are provided to the end that, while thepiston is returning, it will cause the slidable extension to return toits original position One such means comprises an extension of thepiston rod beyond the face of the piston and into the slidable extensionsleeve and a cross pin carried by such rod and engaging slots in thewall of the extension, the slots being sufficiently elongated that theywill not interfere with the firm abutting engagement between the pistonand the extension, as the measuring chamber is closed, but will beengaged by the pin on the return stroke of the piston to be therebyreturned to the exact position at which the extension existed prior toits abutment by the piston. Because the piston thus reciprocates acrossthe space separating the two cylinder segments, whenever the piston isin its rearmost position, the measuring chamber within the forwardcylinder segment is free to fill with the liquid refrigerant moving fromthe supply tank through the inlet conduit and port into the fluidchamber surrounding the cylinder without the need for spring-loadedvalves, etc. At the same time, while the piston is in its rearwardposition, the residue of fluid within the measuring chamber iscompletely exposed to that within the chamber surrounding the cylinder,so that any vapor in the form of bubbles such as might have beendeveloped by the generation of the heat of the pumping can freely passupwardly through the liquid and out the vapor-release or bubblereturnport and back to the supply tank. This vapor release not only insures abubble-free liquid within the pump, but also transmits the vapor to thesupply tank to increase the pressure upon the liquid there to preserveit in its liquid state and to insure that all of the fluid movingthrough the inlet conduit will be under greater pressure than thatwithin the chambers of the pump. Toward the same end, the fact that theportion of the cylinder subjected to the pressure of the dispensingmovement of the piston is completely surrounded by the refrigerant,which is in free communication via the two conduits with the supplytank, insures that any heat developed during the pumping operation willbe readily carried from the pumping area, where the greatest heat islikely to be generated, to the supply tank, thus tending to maintain thetemperature of the entire fluid the same and preventing any temperatureinduced pressure increases of the fluid in the pumping area comparedwith that in the supply tank,

Thus it can be seen that the pump of the present invention, by virtue ofits large annular opening through which the liquid passes into itsmetering chamber eliminates the need for spring-loaded orpressure-actuated valves, thereby allowing unrestricted flow of theliquid even under the smallest pressure differential. At the same timeit utilizes the hydrostatic head of the liquid to insure a constantpressure differential between the supply and the pump to promote areliable liquid flow. Additionally, the novel construction not onlytends to eliminate temperature differentials in the fluid throughout thesupply, metering and dispensing assembly but also minimizes the effectsof such temperature differentials as do occur.

in a modification of the pump according to this invention further meansmay be readily adapted for automatically compensating for thermallyinduced density changes in the fluid so that the metered volumedisplaced on any one cycle of the pump will automatically increase asthe liquid density decreases, or vice-versa, so that each stroke of thepiston will displace exactly the same desired weight of the refrigerant.in this manner, it is only necessary to control the number of dischargecycles of the pump to insure that a reasonably accurate weight amount ofthe fluid will be placed into the refrigerating system. The volumeadjustment is achieved by constructing the above-mentioned cross pin ofa bimetal or other thermally responsive material such that, as thetemperature of the fluid increases (whereby its density will decreaseand a greater volume must be measured for a given weight) the pin willbecome rearwardly bowed so that upon the return stroke of the piston,the cylindrical extension sleeve will be pulled farther into the spacebetween the cylinder segments, thereby effectively increasing the volumeof the liquid that will be within the forward cylinder segment when itis closed by contact with the forward-moving piston. Conversely, if theliquid is relatively cooler and more dense and a lesser volume ofmaterial is to be metered by each piston stroke, the cross pin will havebecome forwardly bowed, so that upon the return stroke of the piston theextension sleeve will not have returned so far, and a smaller chamberwill be defined upon contact of the piston head with the extensionsleeve.

The refrigerant supply dispensing and metering assembly above-describedis such that it can be conveniently installed in a portable unit incombination with a vacuum pump for use in directly, quickly andpositively evacuating the system of refrigerant before the new charge isto be introduced. For accomplishing the sequential association of theevacuating and I filling means with the automotive air-conditioningsystem, the

present invention also comprises connector means in the form of aconnector yoke assembly having a high-pressure chamber and alow-pressure chamber, each of which is associated with a pressure gaugeand with a fitting for connection respectively with the high-pressureand low-pressure sides of the air-conditioner compressor. The yokecarries a connector fitting and passage in communication with both ofsaid chambers and adapted for selective association withliquid-dispensing pump and the vacuum pump, and is further characterizedby a valved passage communicating between the high pressure andlow-pressure chambers therein so that they will be in communication whena vacuum is drawn through the connector passage but the low-pressurechamber will be isolated upon the application of pressure to theconnector passage.

The invention thus generally described may be more clearly understood byreference to the following detailed description of certain specificembodiments thereof, in connection with which reference may be made tothe appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a schematic illustration of a refrigeration system servicingapparatus according to the present invention.

FIG. 2 is a wiring diagram of the electric circuitry for energizing theunit illustrated in FIG. 1.

FIG. 3 is a plan view in partial cross section of the novel meterlng anddispensing pump according to the present invention.

FIG. 4 is an enlarged fragmentary view in cross section of the forwardend of the piston illustrated in FIG. 3, modified to provide thetemperature compensation feature of the present invention.

FIG. 5 is a plan view in partial cross section of the connector yokeassembly for associating the servicing unit of the present inventionwith a refrigeration system, particularly an automotive air-conditioner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to, FIG. I, theservicing apparatus of the presentinvention comprises a refrigerantsupply tank or reservoir 10 which is a closed chamber for housing thesupply of refrigerant which exists within the closed tank in the form ofa liquid 11 and a gaseous phase 12. For safety and convenience the tankmay also be provided with a pressure-relief valve 13 to protect againstexcessive pressure build up which might cause explosion, a bleed valve14 to relieve the vapor pressure within the tank, as for example tofacilitate the filling thereof, but which is normally closed, and asight glass 15 in communication with the interior of the tank 10 toserve as a liquid-level indicator. A filling conduit or fitting having afill valve 16 may be employed for filling the tank via the ports atwhich the sight glass communicates with the interior.

At or near the bottom of the tank 10 is the supply or pump fill linefitting 17, which via the filling conduit 18 is associated with theinlet port 19 of the pump 20. As illustrated, the pump is positionedbelow the supply tank 10 so that the hydrostatic head of the liquidwithin the conduit 18 and the container 10 will promote the flow of theliquid into the pump under the influence of gravity. The pump 20 is alsoprovided with a vaporrelease or bubble-return outlet 21, which, via thevaporrelease conduit 22, is associated with another fitting 23associated with an opening in the tank 10 which is either above thelevel of the liquid normally maintained therein or is extended to apoint above such liquid level by a stack such as 24 extendingupwardly'through the liquid in the tank and opening into the gaseousatmosphere above it. The pump, to be described in greater detail, is areciprocating positive-displacement piston pump driven by the eccentricor cam 25, which is rotatably driven by the electric motor 26. Thedischarge valve and fitting assembly 27 of the pump is supplied with adischarge conduit 28 which, again for the sake of safety, may beprovided with a high-pressure (on the order of 600 pounds per squareinch) pressure relief valve 29, and to insure that the discharge conduit28 will be completely filled with liquid at the time the chargingoperation begins, a lowpressure charge-relief valve" 30. The end of thedischarge conduit is supplied with a female quick-connector fitting 31,ultimately to be connected to the high-pressure side of therefrigeration system to be serviced and, in the case of the presentinvention, to be so connected via a connector yoke as sembly to bedescribed in greater detail. The apparatus also includes a motor-drivenvacuum pump which, via the vacuum line and the female quick connectingcoupler at the end thereof, is ultimately associated with both the highand low sides of the refrigeration system being serviced and again, inthe case of the present invention, is so connected by a connector yokeassembly. The vacuum line 33 may also be provided with a pressure-reliefvalve 35 operable at a very low pressure, upon the order of 1 pound persquare inch, to protect against damage if the system is for some reasonunder pressure when the vacuum pump is connected.

The above-described components are electrically energized for operationaccording to the wiring diagram illustrated in FIG. 2, wherein theelectrical energy is introduced to the circuit at the terminals 36 and36a corresponding to the prongs of a conventional power plug. The motorof the vacuum pump 32 is energized by a first circuit componentconsisting simply of the fuse 37 and the conventional starting relay 38and, as shown, may be so arranged that the vacuum pump operates at alltimes that current is supplied to the system, allowing it to stay heatedto reduce the contamination of the pump oil by refrigerant, air,moisture, etc. An indicator light may also be supplied in this circuitto show that the total apparatus is being supplied with the necessaryelectrical power.

The pump motor 26 is a conventional alternating current electric motor,the circuit for which comprise the fuse 39, the normally closed stopswitch 40, the normally open start switch 41, the counter switch 42, andthe starting relay 43. With power supplied across the main powerterminals 36 and 36a and the starting switch 41 and counter switch 42 inclosed position starting relay 43 will close and electricity will flowthrough the entire circuit of the pump motor 26, thereby driving thesame. The actuation of the starting relay 43 energizes the auxiliarycontacts 46 and 47 so that the starting switch 41 will be bypassed andelectric current will flow through the pump motor circuit, even afterpressure is removed from the starting switch 41 and it opens. At thesame time, the closing of the auxiliary contacts 46 energizes the pumpstroke switch 48 and the pump stroke counter solenoid 49, which, alongwith the counter switch 42, are part of the digital counter which may bemechanically coupled with the pump by a finger such as 48a (in FIG. 1)which is moved each time the eccentric movement of the cam on the pumpdrives the pistonfThe counter may be set for a given number of pulses orpump cycles at the conclusion of which, after each cycle has beencounted by the mechanical coupling of the pump to the pump stroke switch48, will cause the counter switch 42 to open, thereby breaking thecircuit powering the pump 26 and causing it to stop. The counter switch,which is a mechanical part of the digital counter, is such that at anyposition other than zero, it will be closed. Thus, if the counter is setat 200, the switch will be closed and the actuation of the start buttonwill cause the refrigerant pump 26 to be energized and to run through200 cycles which will be sensed by the stroke switch 48 and its solenoid49 until the counter returns to zero, at which point the counter switch42 will open and the pump will stop. If it is desired to stop the pumpbefore the 200 strokes have been counted or at any time during thecounting thereof, depression of the stop switch 40 will break thecircuit and stop the refrigerant pump which may be again started howeverand will operate for the remainder of the previously desired number ofpulses determined by the original setting of the counter until thecounter reaches zero, at which point the switch 42 will open and thecircuit be deenergized.

Referring now to the more detailed illustration of the pump in FIG. 3,the same is driven by the motor 26 and its rotatably driven shaft 50, towhich is affixed, as by the set screw 51, the cam or eccentric withinthe ball bearing as sembly 52 whereby the rotary motion of the driveshaft is transmitted into reciprocal motion in the plane of movement ofthe piston rod 53, such movement being actually accomplished by theresponse of the shell 54 (to which the piston rod is affixed) to themovement of the cam 25 transmitted through the bearings 52. At theforward end of the piston rod 53 is what may be considered aconventional piston 55, except that it is provided on its face withseating and abuttment means 56 to be hereinafter explained. Contrary tothe usual case, however, the piston rod does not terminate at theprincipal piston 55 but extends therethrough and projects therebeyond ina piston rod extension 57 to the forward end of which is affixed atransversely extending bar or pin 58. In the illustration of FIG. 3 thepiston is in its most completely withdrawn position and as the cam oreccentric 25 is rotatably driven, its association with the piston rodvia the bearings 52 and shell 54 will cause the rod and the piston 55 tomove forward from the position shown and then return in what representsone complete metering and dispensing cycle. The rod to the rear of thepiston is provided with conventional packing, bushings, etc. to insure aliquid-tight seal therearound, in spite of the axial movement of the rodthrough the sealing means.

Of particular significance to the present invention is the fact that thecylinder in which the piston moves is composed of two axially alignedbut axially spaced segments 59 and 60 which, taken together, might beregarded as a split cylinder characterized by the circumferential gap61. As can be seen, the piston rod is principally mounted and housedwithin the rearward cylinder segment 59, and the piston head 55 itselfresides therein when the rod is in its completely withdrawn position. Asthe piston 55 moves forward under the influence of the eccentric motion,however, it moves into the forward cylinder segment 60, wherein theactual metering and dispensing action takes place in a manner to behereinafter described. An important feature of the forward cylindersegment 60 is the slotted extension sleeve 62 which may be regardedeither as an extension of the piston head 55 or an extension of theforward cylinder segment 60. The extension sleeve 62 is nonethelessslidable within the forward cylinder segment 60 and is of such adiameter that its outer surface is in contact with the inner surface ofthe cylinder segment 60, to the extent that the contact does notsubstantially interfere with the sliding motion of the sleeve 62 on theone hand and that the use of conventional rings or circumferential sealssuch as 63 will provide a fluidtight association between the contactingsurfaces. The extension sleeve 62 is provided at opposite points on itswall with the elongated slots 64 and 65, in which the cross pin 58 willfreely move during a part of its movement in response to thereciprocation of the piston rod 53 and its extension 57. in this regardit is to be noted that the length of the pin exceeds the inside diameterof the extension sleeve (whereby it may abut against the extremities ofthe slots), but is of course less than the inside diameter of the maincylinder segment 60.

The components providing the cylinder segments 59 and 60 are held intheir axially aligned and properly spaced relationship by the pump bodycylinder or jacket 66, which is completely closed around the cylindersegments except for the two openings to accommodate the inlet fitting 19and the hubble-return fitting 21 previously described. The cylinder body66 thereby defines a liquid chamber surrounding substantially all of thecylinder segments 59 and 60, and what is of critical importance,completely surrounds the circumferential gap 61 between the two segmentsand the forward cylinder segment wherein the metering and dispensing isto take place. It is also to be observed that in the manner ofconventional pumps, the forward cylinder segment is in communicationwith a discharge or dispensing port 67, which is provided with apressure-relief valve 68, which is normally closed and opens only aspressure is applied under the influence of the forward motion of thepiston acting against the liquid within the forward cylinder segment 60,to allow the liquid in the pump to be discharged through the dischargeconduit fitting 69.

Considering now the operation of the pump illustrated in FIG. 3, it isto be recalled from the description of FIG. 1 that the refrigerantliquid from a supply source is caused to flow, principally under theinfluence of gravity, through the pumpfilling conduit 18 and the inletfitting 19, whereupon it will completely fill the chamber 70 defined bythe pump body 66 and the cylinder segments 59 and 60. In addition,however, when the piston 55 is in its rearward or beginning position, asshown in FlG. 3, the liquid can freely pass through the cylinder gap 6]and occupy the chamber within the forward cylinder segment as it ismodified somewhat by the presence of the extension sleeve 62. In thisregard the gap 61 may be considered as the equivalent of the inlet portfor the measuring-dispensing chamber 71; but it is to be observed thatit is characterized by the important differences that it requires novalving or other pressure actuated means to permit the flow of theliquid into the chamber 71 and that it is substantially larger thaninlet ports customarily employed, so that complete filling of thechamber is assured, even where the pressure differential or hydrostatichead promoting the flow of the liquid is normal. Reference to FIG. 1will also disclose that, since the bubble-return fitting 21 is also incommunication with the refrigerant supply the liquid will flow freelyinto the bubblereturn fitting 21 and the vapor-release line 22.

During its intake stage, when the piston is in its rearward position asshown in FIG. 3, the liquid refrigerant is free to flow under verylittle pressure differential into the metering chamber 71 to completelyfill the same. Then, as the piston 55 moves forward, its face 56 willabut against the opposite face 72 of the extension sleeve 62 which,because ofthe liquid seal between the outer face of the extension sleeve62 and the inner surface of the cylinder segment 60, will completelyenclose and precisely define the volume of the metering chamber 71.Then, as the piston continues its forward movement, its influence istransmitted as hydraulic pressure to open the discharge valve 68 andallow the refrigerant liquid to flow through the discharge conduitfitting 69 in a precisely measured amount established by the closure ofthe chamber 71 cffected upon the contact of the piston with theextension sleeve and the forward movement of the piston thereafter,which movement is of course a constant for each cycle and can be closelypredetermined and calculated as a matter of the pump design. As thepiston moves forward, it will also move the extension sleeve forward,preferably to the point at which the forward end of the extension sleeveis at or near the forward face of the cylindrical chamber 71. It is tobe noted that the spacing between the cross pin 58 and the face of thepiston 56 is such, relative to the length of the slots 64 and in theextension sleeve, that the cross pin 58 will not contact the forwardedges of the slots 64 and 65, because the extension sleeve will beconstantly urged forward by its contact with the piston face 55 ratherthan any contact between its slots and the cross pin. Once the pistonhas achieved its forwardmost position, however, the hydraulic pressureupon the liquid refrigerant remaining in the chamber will be removed,whereupon the discharge valve will close and the piston will commenceits withdrawal, during the course of which the piston face 56 willseparate from the extension sleeve 62. which will therefore remainunmoved from its forward posi tion within the forward cylinder segment60 until such time as the rearwardly moving piston brings the pin 58into contact with the rear ends of the slots 64 and 65. The continuedrearward movement of the piston will then slide or drag the cylinderextension back to the predetermined position at which it is shown in H0.3, where the pumping cycle is ready to begin again, and the annularopening between the two cylinder segments is again opened to allow thefree and unrestricted flow of the fluid into the metering and dispensingchamber 71.

A unique feature of this pump which makes it particularly adaptable foruse with low boiling point liquids, in addition to the fact that it canaccommodate the movement of such liquid under very nominal pressuredifferentials, is the fact that the construction and arrangement ofparts allows the principal working area of the pump, especially the areasurrounding the cylinder wherein the movement of the piston takes place,to be completely surrounded by the fluid itself. The fluid in thislocation acts as a heat removal medium, thereby preventing thetemperature in the working area of the pump from becoming so great as tocause any counter pressure to flow of the liquid. Of course, as the lowboiling liquid picks up heat, as for example in the area surrounding theforward cylinder segment 60, it has a tendency to vaporize, and againthe construction and arrangement of parts according to the presentinvention provides a unique advantage in that the vapor, which is in theform of bubbles, is free to rise (keeping in mind that the pump isalways mounted at such an angle that the vapor release fitting 21 isabove the inlet fitting 19) so that the bubbles and the increased vaporpressure they represent are free to rise through the bubble-returnfitting and conduit up to the supply reservoir, wherein the vapor willoccupy the space in the reservoir above the liquid level, thereby addingto the pressure tending to promote the desired liquid flow, rather thanto detract therefrom.

In a modification of the pump according to the present invention,demonstrating its unique adaptability to the handling of refrigerants orother liquids characterized by a high coefficie nt of thermal expansion,the cross pin 58a in FIG. 4 (corresponding to the cross pin 58 in FIG.3) is composed of a bimetallic or other thermally responsive material sothat, as its temperature becomes elevated for example, it will becomerearwardly bowed or distended as shown. As the piston rod returns to itsrearwardmost position, the effect of the pin thus bowed acting againstthe slots 64 and 65 will be to cause the extension sleeve 62 to return agreater distance toward the piston when it is at rest where theextension sleeve will remain until it is again closed by seating contactwith the face of the piston 56. At this closure of the metering anddispensing chamber 71, since the extension sleeve extends beyond theextrernities of the cylinder segment 60, the metering chamber is therebynominally enlarged. When it is considered that the pin 58a is constantlysurrounded by the refrigerant being metered and dispensed, it followsthat the pin will attain and maintain the temperature of the refrigeranteven as it may rise or fall, and that, as the temperature rises, forexample, and the refrigerant accordingly becomes less dense, therearward bowing of the pin will cause an enlargement of the metering anddispensing chamber, which is directly proportional to the decrease ofdensity of the liquid being measured and dispensed, so that regardlessof the temperature of the refrigerant and its density, a constant weightof the liquid will be supplied upon each pumping cycle. Thus, althoughthe pump is truly a volumetric pump, the automatic adjustment thereof todensity changes is such that the pump may be considered to begravimetric, at least to the extent that it dispenses a constant weight,regardless of volume change. This is true, of course, in the case of areverse temperature change, wherein the liquid within the pump is lowerthan that at which it was designed to operate under normal conditions,as a result of which the fluid will be more dense and a small volume.should be pumped for a given weight. In such circumstances, the bimetalelement will become forwardly bowed, as a result of which, upon thereturn stroke of the piston, the extension sleeve will not be moved asfar and will remain in fact in such a condition that, when it iscontacted by the forward moving piston, a smaller metering chamber willbe thereby defined and a smaller volume of the more dense fluid willthereby be discharged for the particular pumping cycle. The parts are ofcourse so designed and calibrated that the reduction in volume preciselycompensates for the increase in density with the result that the sameweight of liquid will be dispensed.

The apparatus heretofore described, including particularly the novelpump illustrated in FIGS. 3 and 4, and the vacuum pump assembledin aunitary structure may then be conveniently associated with arefrigeration system such as an automotive air-conditioner for servicingoperation by means of the connector yoke assembly illustrated in FIG. 5.The connector yoke comprises a blocklike member 75, having a main boreor passage 76 which is divided generally into a low-pressure chamber 77and a high-pressure chamber 78, which are separated by a valve mechanismcomprising a valve-mounting sleeve 79 and a stemmed valve slidabletherein, comprising a stem portion 80 and a seating portion 81 forseating against a suitably finished and positioned seating surfacewithin the passage 76. In fluid communicating relationship with the mainpassage 76 and projecting from the block is a connector coupling such asthe male quick connector 82, which, in the well-known manner of quickdisconnect couplers, is provided with a protruding seating surface 83,with valve means 84 opening thereon, so that upon the insertion of acompanion female segment over the seating surface 83, the valve means 84will be opened and there will be free fluid communication through theconnector to the main passage 76. The operation of the valve components79, 80, 81, and 85 is such that, when a fluid under pressure isintroduced into the block via the connector 82 which is in directcommunication with the highpressure portion 78 of the main passage 76,the valve 81 will close against the seat 85, thereby isolating thelow-pressure portion of the channel and keeping the pressure and thefluid under pressure confined to the high side 78. Conversely, if anegative pressure or a partial vacuum is created within the main channel76 as by the connection ofa vacuum pump hose to the connector 82, thevalve component 81 will be withdrawn from its seat, and both the highand low-pressure sides of the channel within the connector block will bein free fluid communication with the connector and the pressureinfluences being introduced thereby. The high-pressure chamber 78 isalso in fluid communication with a hose or hose-fitting receptacle 86and a pressure gauge receptacle 87; and similarly, the low-pressure sideis provided with a hose or hose-fitting receptacle 88 and a lowerpressure gauge or fitting 89. The gauge receptacles 87 and 89 are thenprovided with the high-pressure gauge 98 and the low-pressure gauge 91respectively and the hose receptacles 86 and 88 are then fitted with ahigh-pressure hose 92 and a low-pressure hose 93 respectively, which arein turn fitted at their opposite ends with suitable connectors 94 and 95for releasable connection to appropriate fittings on the high side andlow side respectively of the refrigeration system to be serviced.

In the servicing of a refrigeration system, such as an automobileair-conditioner, the connector assembly above described is firstconnected to the air-conditioner by the application of the connectors 94and 95 to companion fittings associated with the high and low sides,respectively, of the unit. Since, before a precisely measured quantityof refrigerant can be introduced into the air-conditioner, all of theresidual refrigerant as well as accumulated moisture and vaporouscontaminants must be removed, the first operation is therefore theconnection of the vacuum pump hose 33 in FIG. 1 via the female coupler34 thereof with the male coupler 82 of the connector yoke block. Thevacuum pump is thereupon operated until a constant relatively lowpressure of on the order of 28.8 inches of mercury (depending upon thealtitude and atmospheric conditions in which the system is beingserviced) is achieved, whereupon the vacuum coupler is removed from thefitting 82, leaving the conduits 92 and 93, as well as the refrigerationsystem and the connector yoke block with which they are associated,enclosed and sealed off from the atmosphere. Under this condition, thelow-pressure gauge may be observed for any noticeable rise for a periodof approximately 60 seconds to detect any substantial leak in thesystem. While the pump is operating, the valve 81 is removed from itsseat so that both the high and low-pressure sides of the system areexposed to the influence of the vacuum, thereby to hasten 1., andfacilitate the complete removal of moisture and noncondensibles from thesystem.

If no leaks are observed during the interval of the creation andisolation of the vacuum within the system, the quick connector femalecoupler 31 of the pump discharge conduit 28 is then connected to themale connector 82, and the pump caused to operate for the previouslydetermined number of cycles necessary to provide the exact amount ofweight of refrigerant desired in the system. The pump may be designed,for example, to deliver l/l of a pound of refrigerant upon each forwardstroke of the piston; and the digital counter employed to monitor thestrokes may be of the 3-column variety. Accordingly, if 3 pounds ofrefrigerant are desired, the counter may be set at 300 before the pumpis activated by the pressing of the start button, thereby closing theelectrical circuit energizing the motor, which continues to operatethrough the desired 300 cycles at which point the counter switch, hav'ing sensed the number of cycles through its electricalmechanicalconnection to the pump, opens, to break the electrical circuit and stopthe pump.

During the course of the filling stage, a more effective leak check maybe made of the system by stopping the charging operation after arelatively small amount (on the order of onehalf pound) of refrigeranthas been introduced in the system. This may of course be achieved in thecase of the embodiment here considered by simply pressing the stopbutton after the digital counter has indicated 50 pumping cycles havebeen completed. While the operation is thus stopped, conventional leakdetecting devices may be used to trace the system for refrigerantleakage. if the system is found to be sound at this point, the balanceofthc desired full charge may then be transmitted by again pushing thestart button and allowing the pump to continue to operate until theadditional 250 pumping cycles have returned the counter to zeroposition, at which the counter switch opens and the pump is stopped.

Further advantages of the apparatus of the present invention reside inthe fact that, while the refrigerant is being introduced into the systemvia the connector yoke block assembly described in connection with FIG.5, the low-pressure side of the system, by operation of the valve 81, iscompletely shut off from the fluid flow. Because of this, all of thecharging is done into the high side of the system, making theintroduction of the refrigerant in its liquid stage feasible andunharmful. Because the prior art devices and procedures have requiredfilling the high and low sides of the system simultaneously or fillingthe low side only, it has been necessary that the refrigerant be in agaseous state at the time it is introduced, since liquid flowing intothe low side causes damage of the parts therein and especially as to thecompressor and a washing away of the lubricant necessary for theefficient operation of such parts. A further advantage of the apparatusof the present invention resides in the fact that, during and after thecharging of the system, which may be accomplished even while the systemis operating, the association of the high-pressure and low-pressuregauges 90 and 91 respectively with the high and low sides of the systemwhile it is operating provide the opportunity for an easy inspection todetermine whether the system is operating at the design pressures. Thismay be accomplished because the two sides of the system are isolated bythe closure of the valve 81 both during and after the filling operation.

While the foregoing invention has been described in considerable detailin connection with a preferred embodiment and a modification thereof, itis to be understood that the foregoing particularization is for thepurpose of illustration only and does not limit the scope of theinvention as it is defined in the subjoined claims.

lclaim:

1. A refrigeration system servicing apparatus comprising a refrigerantsupply reservoir, a liquid metering and dispensing pump positioned belowsaid reservoir, a vacuum pump, connector means for selectively andalternatively associating said metering and dispensing pump and saidvacuum pump with the refrigeration system, wherein said metering anddispensing pump comprises a circumferentially split cylinder, at leastthe split portion of which is surrounded by a liquid chamber, at leastthe upper portion of which is provided with port means in fluidcommunication with said reservoir whereby liquid from said reservoir isallowed to flow freely into said chamber and the gas formed by thevaporization of said liquid in said chamber is allowed to flow freelyupwardly into said reservoir, a positive-displacement pistonreciprocally driven and so positioned within said cylinder that the faceof the piston on each stroke thereof moves from a position rearwardly ofthe front edge of said split to a point substantially forward of frontedge, a cylindrical extension sleeve in fluid-sealing engagement withand slidable within said cylinder forwardly of said split, saidextension sleeve being positioned for seating and liquid-sealing contactwith the piston face and for forward movement as the piston movesforward, and means for sliding said sleeve rearwardly as the pistonmoves rearwardly, whereby the reciprocal movement of the piston causes acorresponding reciprocal movement of the extension sleeve within thecylinder forwardly of said split.

2. A refrigeration system servicing apparatus according to claim 1wherein said connector means are unitary means comprising a connectorblock having a high-pressure chamber and a low-pressure chamber, each ofwhich is associated with a pressure gauge and with a fitting for conduitconnection respectively to the high-pressure side and the low-pressureside of the system to be serviced, an intermediate passage connectingsaid chamber, a coupler fitting in fluid transmitting communication withboth of said chambers adapted for selective association by conduitconnection with said metering and dispensing pump and said vacuum pump.

3. A refrigeration system servicing apparatus according to claim 2wherein said intermediate passage is provided with valve means which arenormally open when there is no pressure or a negative pressure withineither of said chambers but are closed upon the application of pressureto said high-pressure chamber thereby to isolate the same from saidlow-pressure chamber.

4. A refrigeration system servicing apparatus according to claim 1wherein said port means comprise two ports in fluid communicatingassociation with said reservoir and said liquid metering and dispensingpump is positioned that one of said ports is relatively above the other.

5. A refrigeration system servicing apparatus according to claim 4wherein the upper most of said ports is connected to said reservoir by aconduit discharging into the reservoir at a point above the liquid leveltherein.

6. A refrigeration system servicing apparatus according to claim 1wherein said means for sliding said sleeve rearwardly are thermallyresponsive and adjust the degree of rearward movement of the sleeve uponthe rearward movement of the piston whereby an increase in temperaturewill cause the sleeve to move more to the rear and a decrease intemperature will cause the sleeve to move less to the rear therebyrespectively increasing or decreasing the volume of the metering chamberpartially formed by said sleeve upon its contact with the piston faceand compensating for thermally induced changes in the liquid densitywhereby a constant weight of liquid will be dispensed upon each forwardstroke of the piston regardless of its temperature.

7. A liquid metering and dispensing pump comprising a cylinder composedof coaxial and axially spaced front and rear hollow cylindricalsections, a jacket at least partially surrounding said cylinderincluding the space between said sections to form a liquid chambertherearound, port means in said jacket at least near the top of saidliquid chamber in fluid communication with a liquid supply reservoir, apiston reciprocally driven and so positioned within said cylinder thatits reciprocating movement carries the face thereof from a positionrearwardly of the front cylindrical section substantially into saidfront section, a valved discharge outlet from said front section, ahollow cylindrical extension sleeve slidable reciprocates within thecylinder, it will sequentially contact and form liquid-sealing seatingengagement with said sleeve thereby enclosing a metering chamber withinthe front cylinder section, the piston and sleeve will move forward todispense the metered liquid through said discharge outlet, and saidsleeve will be returned to its original position whereupon the piston,in its rearward movement, will separate therefrom and move to the rearof said front section whereupon said metering chamber will be opened atsaid axial space between said sections to the fluid within said chamber.

8. A liquid metering and dispensing pump according to claim 7 whereinsaid port means comprise two ports, one of which is elevated relative tothe other, wherebyliquid may flow from said reservoir into said chamberand any gas formed by the vaporization of said liquid in said chambermay flow from said chamber into said reservoir via the relativelyelevated of said ports.

9. A liquid metering and dispensing pump according to claim 7 whereinsaid means for causing said sleeve to slide rearwardly are associatedwith said piston and comprise a rod projecting forwardly from the facethereof and a cross-pin through said rod engaging diametricallypositioned openings in the wall of said sleeve.

10. A liquid metering and dispensing pump according to claim 9 whereinsaid openings in the wall of said sleeve are elongated and the lengththereof axially of the sleeve is greater than the distance traveled bythe piston in moving from its rearward most position to the abutment ofits face against said sleeve whereby said sleeve will move forwardlyonly in response to its abutting contact with the face of the piston,but will move rearwardly in response to the abutting engagement betweensaid cross-pin and the rearward edges of said openings. p

11. A liquid metering and dispensing pump according to claim 9 whereinsaid cross-pin is composed of a thermally responsive metal which becomesrearwardly bowed upon a temperature increase and forwardly bowed upon atemperature decrease.

